From at least the Neolithic period to the nineteenth-century, loaf breads were baked in wood fired ovens. Of course, there were always exceptions. Loaf breads can be baked under pots over which embers are shoveled and the Egyptians are known to have systematically baked large loaves in large clay pots that were broken to release the finished breads, but by and large, loaf breads and wood fired ovens have long been paired. Today, wood fired bread ovens is largely the purview of a comparative few commercial bakeries — the Poilane Bakery in Paris being the most famous user of wood fired ovens — pizza restaurants, and the backyard enthusiast.The European country tradition of baking bread in wood fired ovens is now nearly extinct.

What is a traditional bread oven? A traditional bread oven is a chamber enclosed by a refractory material such as stone, brick, adobe, or refractory concrete. These ovens were traditionally heated with faggots, wood, straw, or some other locally available combustible material. Ovens can also be heated with coal, steam, or flames generated by burning fuel oil, propane, or natural gas. Traditionally, bread is baked in the oven after the embers and ash are swept out of the oven. Thus, the heat source used to fire the oven has no bearing on the taste of the finished loaf.

More exactly, what is “a refractory material?” A refractory material is one that can withstand the thermal shock of direct flame. Just because a material is refractory, however, does not make it suitable for a bread oven. Materials that are appropriate for bread ovens must be both refractory — able to withstand the shock of fire — and also good heat sinks. Examples of such materials include common red brick, adobe (clay and straw), many kinds of stone, clay, refractory concrete (a concrete specifically manufactured to withstand high heat), or even a mixture of garden dirt and cement. What you don’t want to use is a refractory material that is a good insulator, such as materials used to build kilns. By tradition, ovens are made with whatever material is cheapest and most readily available to the oven builder. [Note 1]

How does a traditional bread oven work? Another name for a traditional bread oven is a “retained heat oven.” The walls of the oven store heat from a fire built built within the oven chamber. After the fire has sufficiently heated the walls of the oven all embers and ash are swept out of the oven. The air within the oven is thus heated by the heat given off by the oven walls as they cool. This means that bread is baked in an oven that is always getting cooler. This is called baking in a “falling oven.” One implication of baking in a falling oven is that one may need to start baking when the oven is hotter than one would in an oven maintained at a steady temperature by a thermostat.
If you plot the temperature of your oven against time on graph paper you will learn the rate at which your oven cools and thus how many hours you can bake at any given temperature.
Historically, loaf breads were baked on retained heat only. However, bakers who were producing multiple batches of rolls baked with a fire burning inside the oven just as we see in the ovens operated in pizza restaurants.
The unique quality of bread baked in a wood fired oven comes from the steam that builds up in the oven from a full load of bread.
Here is how a traditional wood fired bread oven is operated to bake a full load of bread.

1. A hot fire is burned inside the oven until all the smoke had burned off the oven walls and they are white hot. This usually takes from one and a quarter to two hours, depending on the size of the oven and how cold it is to start. One and a half hours is a typical firing period for a home oven.
2. After the oven is hot and the fire dies down the embers are spread evenly across the oven floor. After some time, for example, ten minutes, the embers and ash are then swept out of the oven. A garden hoe is a good tool for this job.
3. Next, the oven floor is mopped. A wet rag on the end of a long pole, or an old broom dipped in water work well as mops. A freshly cut branch from a fir tree will also work.
4. At this point the oven is too hot to bake bread. The oven is left to cool until it reaches the temperature when the bread can be loaded. Experiment with your oven to determine whether it should be cooled with the door open or closed. Twenty or thirty minutes may be sufficient cooling time, though this will depend on your oven and your style of firing.
5. In the past it was common to leave a pile of embers in the oven doorway under the doorway arch. This pile of embers creates and updraft which effectively acts as an oven door. The ember door remained in place while the bread was loaded into the oven.
6. After the oven is loaded with bread the iron door is closed. If embers were piled in the doorway, these are swept away before the door is shut. In the past the door was sealed with dirt or clay. The more modern practice is to seal the door with sheets of newspaper, as illustrated in the photograph on the top of this page.
7. After the bread is baked — and baking time depends on both oven temperature and the size of the loaf — the loaves are removed from the oven. In the past it was common for crusty loaves to be cooled bottom-side up top preserve cripiness. [Note]
8. As a rule, it was historic pratict to let bread rest for a day before eating it. Many breads, and particularly those that include some bran and some rye flour, improve in flavor for this one day rest.

When you sweep the embers out of the fireplace you need someplace for them to go. I visited a village in France where the practice was to sweep the embers into a bucket and then for the bakers to sit around roasting sausages over the embers and drinking beer. If you have a small barbecue to accept the embers I am sure you could think of a way to put them to good use.

How do I know how hot it is inside the oven? Ovens can be built with temperature guages embedded within the oven wall and floor. But most home bakers need to rely on intuition and/or on thermometers. For high temperatures you can measure the surface of the oven wall and floor using an infrared thermometer. Once the oven cools to within the range of a kitchen oven you can use a stnadard oven thermometer.

How do you use the oven to bake foods other than bread? An oven is an oven regardless of the heat source. You can bake anything you can bake in a kitchen oven in a bread oven. If all the embers have been swept out of the oven and you are cooking entirely on the heat retained in the oven walls then you are baking on a falling oven. Place foods into the oven when the oven falls to the temperature that is appropriate for it. If you plot the curve of your oven’s heat decay then you will have a good sense of how to plan dishes for the falling oven. At any point in the oven temperature’s fall you can build a booster fire within the oven. A booster fire typically holds the oven at a given temperature. As a rule, recipes that call for long slow cooking, like many stews, or baked beans, were originally cooked, at least sometimes, in the falling heat of the bread oven.
Oven Steam: A deep and wonderful crust is one of the foremost features of wood-oven baked country loaves. Commercial bread ovens have ways of introducting steam into the oven to replicate the steamy atmospher of a traditional bread oven. A full load of bread in a large oven, such as the one pictured on this page, might bake one-hundred-fifty pounds of bread (68 kg) in a singel batch. This much bread dough would contain about sixty pounds of water, excluding water in the grain itself. [Note 2] If dough shrinkage during baking is around 15%, then approximately twenty-three pounds (10kg) of water will be vaporized during the baking process. With a sealed oven door the bread bakes in an exceedingly humid atmosphere.

• Oven temperature drops as it fills with steam.
• The relatively cooler moist environment promotes the development of the crust.
• Newspaper used to stop the oven door becomes wet.

If you don’t fill your oven with bread then you can increase the amount of steam by placing shallow pans of water on the oven floor.

How long does it take to fire the oven? I discuss this in more detail, below, but the typical firing is one and quarter to two hours, with one and a half hours being a good average. An oven three feet in diameter (90cm) fired with bone dry small diamter wood will usuallybe fully fired in about an hour and a quarter.

What are the The best fuel for a flash fire is fuel that burns hot and fast. Tree prunings are perfect, as are small-diameter branches, and construction scraps. Soft wood, such as pine, can be burned in larger diamter pieces, in a large oven, even as split logs.

Bread ovens often put out smoke during the firing process. This happens when there is too much fuel for the amount of oxygen in the oven. Smoke is most common during the inital phases of firing the oven, before the fire has built up to a furnace-like heat.

Always start with dry wood. Ideally, place the wood for the next firing in the oven after you finish baking. Once the fire is established, add wood. Again, small diameter wood is always best. If you only have logs to burn, split them at least into fourths. This is especially imporant if you are burning hard woods. During the initial firing the oven walls turnt black with smoke. As the fire gets hotter it will stop smoking. Eventually, the heat is sufficient to burn off the smoke on the oven walls, and to turn the walls white. About this time in the firing process the gasses sitting just below the ceiling catch fire. This is the kind of secondary combustion that one looks for in fuel efficient wood stoves. The roiling gasses are also beautiful, and make an ever-fascinating spectacle.

You will probably add wood at various times during the firing process. It is important to add wood at a rate the fire can accept. If you push too much wood into the oven at any one time the fire will smoke.
Every time you fire the oven it should get hot enough to ignite the gasses within the oven. I like to keep these gasses burning for fifteen or twenty minutes. Then you can let the fire die down to embers. Spread the embers across the oven floor for even heating. When the embers have burned down to something managable, then pull them out of the oven using a hoe and mop the oven floor. The embers can be put into a barbecue and then used to immediately grill a meal — or a snack. If you are firing the oven for pizza, then push the embers to the side of the oven, and then mop the part of the floor where you will bake the pizza.

[Note 2] Large loaves of bread, such as an eight pound (3.5kg) loaf of rye bread might take three hours to bake.

[Note 3] Using a baker’s formula of 100% flour and 63% water, 150 pounds of dough would contain 95 pounds of flour and 60 pounds of water.

[Note 4] Ovens are damaged by fire. The home baker is unlikely, in a lifetime of baking, to see the damage caused by firing the oven. But commercial ovens do show damage after years of use — even if that might not be for eight or ten or twelve years. It is important, therefore, that commercial ovens are built so they can be repaired.
[Note 4] The typical pre-fabricated oven holds enough heat to bake a load of breads on the heat retained in the oven walls. Considering that an oven that is just three feet in diameter can pack more bread than a family can eat fresh this is sufficient for most home bakes.